CN113258632B

CN113258632B - Power supply device

Info

Publication number: CN113258632B
Application number: CN202110183606.3A
Authority: CN
Inventors: 森本充晃; 杉村一男; 椿和也; 大石英一郎; 重实泰行
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2020-02-10
Filing date: 2021-02-08
Publication date: 2024-02-09
Anticipated expiration: 2041-02-08
Also published as: CN113258632A; US11581747B2; JP7083858B2; US20210249875A1; EP3863143B1; EP3863143A1; JP2021126027A

Abstract

The invention provides a power supply device capable of appropriately charging batteries capable of switching between series connection and parallel connection. In the power supply device (1), a switching unit (40) switches the connection of batteries (10A, 10B) to a series connection or a parallel connection. When the connection of the batteries (10A, 10B) is switched from serial connection to parallel connection and the batteries (10A, 10B) are charged by an external Charger (CG), a control unit (50) switches the connection of the batteries to parallel connection and charges the smaller one of the batteries without switching the connection of the batteries to parallel connection when the potential difference between the Voltage (VA) of the battery detected by a voltage detection unit (30A) and the Voltage (VB) of the battery detected by the voltage detection unit (30B) is equal to or greater than a predetermined threshold value, and switches the connection of the batteries to parallel connection and charges the batteries when the potential difference is less than the threshold value.

Description

Power supply device

Technical Field

The present invention relates to a power supply device.

Background

Conventionally, as a power supply device, for example, patent document 1 discloses a quick charging device including a1 st battery module and a 2 nd battery module, wherein the 1 st battery module and the 2 nd battery module are connected in series when charging and the 1 st battery module and the 2 nd battery module are connected in parallel when discharging.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2018-033263

Disclosure of Invention

Technical problem to be solved by the invention

However, the quick charging device described in patent document 1 may use a series connection and a parallel connection, respectively, according to a charging voltage at the time of charging, but in such a case, it is desirable to appropriately charge the 1 st battery module and the 2 nd battery module.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply device capable of appropriately charging batteries that can be connected in series and in parallel in a switchable manner.

Means for solving the problems

In order to solve the above-described problems and achieve the object, a power supply device according to the present invention includes: a1 st cell and a 2 nd cell, the 1 st cell and the 2 nd cell being capable of charge and discharge; a voltage detection unit that detects voltages of the 1 st cell and the 2 nd cell, respectively; a switching unit that switches connection of the 1 st cell and the 2 nd cell to a series connection or a parallel connection; and a control unit that controls the switching unit to switch connection of the 1 st battery and the 2 nd battery from the series connection to the parallel connection and to charge the 1 st battery and the 2 nd battery by an external charger, wherein when a potential difference between the voltage of the 1 st battery detected by the voltage detection unit and the voltage of the 2 nd battery detected by the voltage detection unit is equal to or greater than a predetermined threshold value, the control unit does not switch connection of the 1 st battery and the 2 nd battery to the parallel connection so as not to charge the 1 st battery and the 2 nd battery to the larger voltage and to charge the 1 st battery and the 2 nd battery to the smaller voltage alone, and when the potential difference is smaller than the threshold value, the control unit switches connection of the 1 st battery and the 2 nd battery to the parallel connection and to charge the 1 st battery and the 2 nd battery.

In the above power supply device, preferably, the control unit controls the switching unit to cause the external charger to be connected to the 1 st battery and to supply a constant current of electric power from the external charger to the 1 st battery for a predetermined period of time, and the control unit controls the switching unit to cause the external charger to be connected to the 2 nd battery and to supply a constant current of electric power from the external charger to the 2 nd battery for a predetermined period of time, the voltage detection unit detects a voltage of the 1 st battery when a constant current of electric power is supplied from the external charger to the 1 st battery, and detects a voltage of the 2 nd battery when a constant current of electric power is supplied from the external charger to the 2 nd battery, the control unit calculates an actual voltage increase per unit time of the 1 st battery based on the voltage of the 1 st battery detected by the voltage detection unit, and calculates a potential difference per unit time of the 2 nd battery based on the voltage increase per unit time of the 2 nd battery calculated based on the voltage of the 2 nd battery detected by the voltage detection unit, and calculates a potential difference per unit time of the voltage of the 2 nd battery based on the calculated per unit time of the actual voltage increase per unit of the 2 nd battery and the voltage of the 2 nd battery calculated by the voltage detection unit of the voltage detection unit, and the potential difference per 1 st battery and the 1 th battery calculated based on the actual voltage of the 1, and charging the 2 nd battery based on the calculated charging time.

Effects of the invention

The power supply device according to the present invention is configured such that when the potential difference between the 1 st battery and the 2 nd battery is equal to or greater than a threshold value, the connection between the 1 st battery and the 2 nd battery is not switched to the parallel connection, and the 1 st battery and the 2 nd battery are charged independently without charging the one of the 1 st battery and the 2 nd battery having a larger voltage but charging the other of the 1 st battery and the 2 nd battery having a smaller voltage, and when the potential difference is less than the threshold value, the connection between the 1 st battery and the 2 nd battery is switched to the parallel connection to charge the 1 st battery and the 2 nd battery. According to this configuration, the power supply device can equalize the voltages of the 1 st battery and the 2 nd battery by charging and then connect the 1 st battery and the 2 nd battery in parallel, and can appropriately charge the batteries that can be switched between series connection and parallel connection.

Drawings

Fig. 1 is a block diagram showing a configuration example of a power supply device according to an embodiment.

Fig. 2 is a diagram showing a relationship between a battery voltage and a remaining capacity (SOC) according to the embodiment.

Fig. 3 is a diagram showing a quick charge example according to the embodiment.

Fig. 4 is a graph showing a relationship between the voltage increase amount and time according to the embodiment.

Fig. 5 is a timing chart showing the voltage equalization process according to the embodiment.

Fig. 6 is a flowchart showing an example of the operation of the power supply device according to the embodiment.

Fig. 7 is a block diagram showing a configuration example of a power supply device according to a modification of the embodiment.

Symbol description

1. 1A power supply device

10A battery (1 st battery)

10B Battery (No. 2 battery)

30A-30C voltage detection part

40. Switching part

50. Control unit

CG quick charger (external charger)

Detailed Description

The mode (embodiment) for carrying out the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. The constituent elements described below include elements that can be easily recognized by those skilled in the art, and substantially the same elements. The structures described below can be appropriately combined. Various omissions, substitutions and changes in the structure may be made without departing from the spirit of the invention.

Embodiment(s)

The power supply device 1 according to the embodiment will be described with reference to the drawings. Fig. 1 is a block diagram showing a configuration example of a power supply device 1 according to the embodiment. The power supply device 1 is mounted on a Vehicle such as an EV (Electric Vehicle), and is a high-voltage power supply device that supplies Electric power to a high-voltage load (for example, an inverter) provided in the Vehicle. The power supply device 1 will be described in detail below.

As shown in fig. 1, the power supply device 1 includes a battery cell 10, a current detection unit 20, voltage detection units 30A and 30B, a switching unit 40, and a control unit 50.

The battery unit 10 is connected to an external quick charger (external charger) CG, and accumulates electric power supplied from the quick charger CG. The battery unit 10 supplies the stored electric power to a high-voltage load such as an inverter. The battery unit 10 is configured to include a battery 10A as a1 st battery and a battery 10B as a 2 nd battery.

The battery 10A is a secondary battery capable of charging and discharging dc power, and is configured to include a plurality of battery cells. Each of the battery cells is constituted by a chargeable/dischargeable secondary battery, for example, a lithium ion battery. Each battery cell and the adjacent battery cell are connected in series with each other. The battery 10A accumulates electric power supplied from the quick charger CG and supplies the accumulated electric power to a high-voltage load unit such as an inverter.

The battery 10B is configured in the same manner as the battery 10A described above. That is, the battery 10B is a secondary battery capable of charging and discharging dc power, and is configured to include a plurality of battery cells. Each of the battery cells is constituted by a chargeable/dischargeable secondary battery, for example, a lithium ion battery. Each battery cell and the adjacent battery cell are connected in series with each other. The battery 10B accumulates electric power supplied from the quick charger CG, and supplies the accumulated electric power to a high-voltage load unit such as an inverter.

The current detection unit 20 detects a current. The current detection unit 20 is provided between the quick charger CG and the battery cell 10, and detects a current of electric power supplied from the quick charger CG to the battery cell 10. The current detection unit 20 detects, for example, a current IA of electric power supplied from the quick charger CG to the battery 10A. Further, the current detection unit 20 detects a current IB of the electric power supplied from the quick charger CG to the battery 10B. The current detection unit 20 is connected to the control unit 50, and outputs the detected currents IA and IB to the control unit 50.

The voltage detection unit 30A detects a voltage. The voltage detection unit 30A is connected in parallel with the battery 10A, and detects the voltage between the positive electrode and the negative electrode of the battery 10A. The voltage detection unit 30A is connected to the control unit 50, and outputs the detected voltage VA of the battery 10A to the control unit 50.

The voltage detection unit 30B detects a voltage. The voltage detection unit 30B is connected in parallel with the battery 10B, and detects the voltage between the positive electrode and the negative electrode of the battery 10B. The voltage detection unit 30B is connected to the control unit 50, and outputs the detected voltage VB of the battery 10B to the control unit 50.

The switching unit 40 switches the connection between the battery 10A and the battery 10B. The switching unit 40 switches the connection of the battery 10A and the battery 10B to a series connection or a parallel connection, for example, based on a switching signal output from the control unit 50. The switching unit 40 includes a switch sw_a, a switch sw_b, and a switch sw_c. The switches sw_a to sw_c may be, for example, semiconductor relays, mechanical relays, or the like, but any switches may be used as long as the current path can be energized or shut off.

The switch sw_a is a switch for switching on or off the current path, and is a switch for connecting the battery 10A and the battery 10B in parallel. The switch sw_a is provided between the connection point P1 and the negative electrode of the battery 10A. Here, the connection point P1 is a connection point connecting the negative electrode of the quick charger CG and a connection line connecting the negative electrodes of the batteries 10A and 10B to each other. The switch sw_a electrically connects the negative electrode of the battery 10A with the negative electrode of the battery 10B by being turned on, and electrically connects the negative electrode of the battery 10A with the negative electrode of the quick charger CG. The switch sw_a is turned off to electrically disconnect the negative electrode of the battery 10A from the negative electrode of the battery 10B, and to electrically disconnect the negative electrode of the battery 10A from the negative electrode of the quick charger CG.

The switch sw_b is a switch for switching on or off the current path, and is a switch for connecting the battery 10A and the battery 10B in parallel. The switch sw_b is provided between the connection point P2 and the positive electrode of the battery 10B. Here, the connection point P2 is a connection point connecting the positive electrode of the quick charger CG and a connection line connecting the positive electrodes of the batteries 10A and 10B to each other. The switch sw_b electrically connects the positive electrode of the battery 10A with the positive electrode of the battery 10B by being turned on, and electrically connects the positive electrode of the battery 10B with the positive electrode of the quick charger CG. The switch sw_b is turned off to electrically disconnect the positive electrode of the battery 10A from the positive electrode of the battery 10B, and to electrically disconnect the positive electrode of the battery 10B from the positive electrode of the quick charger CG.

The switch sw_c is a switch for switching on or off the current path, and is a switch for connecting the battery 10A and the battery 10B in series. The switch sw_c is provided between the negative electrode of the battery 10A and the positive electrode of the battery 10B. The switch sw_c is turned on to electrically connect the negative electrode of the battery 10A to the positive electrode of the battery 10B, and turned off to electrically disconnect the negative electrode of the battery 10A from the positive electrode of the battery 10B.

The switching unit 40 configured as described above switches the connection between the battery 10A and the battery 10B to the parallel connection by turning on the switch sw_ A, SW _b and turning off the switch sw_c based on the switching signal from the control unit 50. The switching unit 40 switches the connection between the battery 10A and the battery 10B to the series connection by turning on the switch sw_c and turning off the switch sw_ A, SW _b. In addition, the switching unit 40 connects the battery 10A and the quick charger CG separately by turning on the switch sw_a and turning off the switch sw_ B, SW _c, without connecting the battery 10B and the quick charger CG. In addition, the switching unit 40 connects the battery 10B and the quick charger CG separately by turning on the switch sw_b and turning off the switch sw_ A, SW _c, without connecting the battery 10A and the quick charger CG.

The control section 50 controls the switching section 40. The control unit 50 is configured to include an electronic circuit mainly including a well-known microcomputer including a CPU, a ROM, a RAM, and an interface, which constitute a storage unit. The control unit 50 outputs a switching signal to the switching unit 40 to switch the connection of the batteries 10A and 10B to a series connection or a parallel connection.

For example, when power is supplied from each of the batteries 10A and 10B to a load (for example, an inverter) during running of the vehicle, the control unit 50 switches the connection of each of the batteries 10A and 10B to a series connection, and supplies power to the load at a high voltage (for example, about 1000V). When the batteries 10A and 10B are charged by the quick charger CG, the control unit 50 switches the connection of the batteries 10A and 10B to the series connection or the parallel connection according to the charging voltage of the electric power supplied from the quick charger CG. For example, when the charging voltage of the electric power supplied from the quick charger CG is a relatively high voltage (for example, about 1000V), the control unit 50 switches the connection of the batteries 10A and 10B to the series connection, and charges the batteries 10A and 10B connected in series with the electric power of the high voltage (for example, about 1000V) supplied from the quick charger CG. On the other hand, when the charging voltage of the electric power supplied from the quick charger CG is a relatively low voltage (for example, about 500V), the control unit 50 switches the connection of the batteries 10A and 10B to the parallel connection, and charges the batteries 10A and 10B connected in parallel with the electric power of the low voltage (for example, about 500V) supplied from the quick charger CG.

After supplying electric power to the load unit by the batteries 10A and 10B connected in series, the control unit 50 performs a process of equalizing the voltages of the batteries 10A and 10B when the batteries 10A and 10B are charged by the quick charger CG of low voltage (for example, about 500V) by switching the connection of the batteries 10A and 10B from the series connection to the parallel connection. The control unit 50 calculates, for example, a potential difference between the voltage VA of the battery 10A detected by the voltage detection unit 30A and the voltage VB of the battery 10B detected by the voltage detection unit 30B. Then, the control unit 50 compares the calculated potential difference with a predetermined threshold value, and if the calculated potential difference is smaller than the threshold value, the control unit switches the connection of the batteries 10A and 10B to the parallel connection to charge the batteries 10A and 10B, since an excessive rush current does not flow between the batteries 10A and 10B due to the potential difference.

On the other hand, when the potential difference is equal to or greater than the threshold value, since an excessive rush current flows between the batteries 10A and 10B due to the potential difference, the control unit 50 does not switch the connection of the batteries 10A and 10B to the parallel connection, but first performs a process of equalizing the voltages of the batteries 10A and 10B. For example, as the equalization processing, the control unit 50 does not charge the battery having a large voltage among the batteries 10A and 10B, but separately charges the battery having a small voltage. For example, in the case where the voltage VA of the battery 10A is smaller than the voltage VB of the battery 10B, the control section 50 does not connect the battery 10B with the quick charger CG but connects the battery 10A with the quick charger CG separately to charge the battery 10A. On the other hand, in the case where the voltage VB of the battery 10B is smaller than the voltage VA of the battery 10A, the control section 50 does not connect the battery 10A with the quick charger CG but connects the battery 10B with the quick charger CG separately to charge the battery 10B.

Next, the equalization process will be described in detail. Fig. 2 is a diagram showing a relationship between a battery voltage and a remaining capacity (SOC) according to the embodiment. Fig. 3 is a diagram showing a quick charge example according to the embodiment. Fig. 4 is a graph showing a relationship between the voltage increase amount and time according to the embodiment. As shown in fig. 2, each battery 10A, 10B determines the use range W1 of each battery 10A, 10B based on the remaining capacity. The use range W1 is generally a range in which the remaining capacity of each battery 10A, 10B is about 30% to about 100%. The batteries 10A and 10B are charged with electric power of a constant current in a range W2 (the remaining capacity is about 30% to 80%) which is a part of the use range W1, and are charged with electric power of a constant voltage in a remaining range W3 (the remaining capacity is about 80% to 100%).

For example, when the quick charger CG is used for quick charging, the batteries 10A and 10B are charged with electric power of a constant current until the battery voltage reaches an upper limit voltage Vmax (the remaining capacity is about 80%) at time T1, and then charged with electric power of a constant voltage after the battery voltage reaches the upper limit voltage Vmax at time T1, as shown in fig. 3, so that the charging current is reduced. While the batteries 10A and 10B are charged with electric power of a constant voltage, the charging current gradually decreases to approach full charge (the remaining capacity is 100%).

As shown in fig. 3, when charging is performed with electric power of a constant current, the remaining capacity of each battery 10A, 10B increases in proportion to time. In addition, when the battery is charged with electric power of a constant current, the voltage of each battery 10A, 10B increases in proportion to time. It is generally considered that the state in which the quick charger CG is used is a state in which the remaining capacity is small, and thus charging is started with electric power of a constant current. In the case of charging with electric power of a constant current, as described above, the battery voltage increases in proportion to time. For example, as shown in fig. 4, if the initial voltage V0, the time t0 of the initial voltage, the charging end time t1, and the voltage V1 of the charging end time t1 are known, the battery voltage Vt (see the following equation (1)) when charging is performed during the charging time t with the electric power of the constant current can be calculated. That is, it is known how much time to charge the battery 10A and the battery 10B in order to eliminate the potential difference from each other, based on the proportional relationship between the battery voltage and the charging time.

Vt＝((V1-V0)/(t1-t0))×t+V0 (1)

Next, an actual voltage equalization process will be described. Fig. 5 is a timing chart showing the voltage equalization process according to the embodiment. The control unit 50 switches the connection of the batteries 10A and 10B to the series connection when the power is supplied from the batteries 10A and 10B to the load unit (for example, an inverter) during the running of the vehicle, and therefore, in the case of charging by the parallel connection, first turns off the switch sw_c. In addition, at this time, the switch sw_ A, SW _b is also turned off.

First, at time T1 shown in fig. 5, control unit 50 detects initial voltage VA0 of battery 10A by voltage detection unit 30A, and detects initial voltage VB0 of battery 10B by voltage detection unit 30B. Next, the control unit 50 turns on the switch sw_a to connect the battery 10A to the quick charger CG alone without connecting the battery 10B to the quick charger CG. Then, the control section 50 supplies the electric power of the constant current from the quick charger CG to the battery 10A for a certain period of time. At this time, a current IA equivalent to the maximum current Imax of the quick charger CG flows through the battery 10A. The control unit 50 turns off the switch sw_a at time T2 after a predetermined time elapses, and detects the voltage VA1 of the battery 10A by the voltage detection unit 30A.

Next, the control section 50 turns on the switch sw_b so as not to connect the battery 10A to the quick charger CG but to connect the battery 10B to the quick charger CG separately. Then, the control section 50 supplies the electric power of the constant current from the quick charger CG to the battery 10B for a certain period of time. At this time, a current IB equivalent to the maximum current Imax of the quick charger CG flows through the battery 10B. The control unit 50 turns off the switch sw_b at time T3 after a predetermined time elapses, and detects the voltage VB1 of the battery 10B by the voltage detection unit 30B.

The control unit 50 calculates the actual voltage increase per unit time of the battery 10A for a predetermined period of time based on the voltage VA1 of the battery 10A detected by the voltage detection unit 30A. The control unit 50 calculates the actual voltage increase per unit time of the battery 10B for a predetermined period of time based on the voltage VB1 of the battery 10B detected by the voltage detection unit 30B.

When the potential difference between the voltage VA1 of the battery 10A and the voltage VB1 of the battery 10B is smaller than the threshold value, the control unit 50 turns on the switch sw_ A, SW _b to switch the connection of the batteries 10A and 10B to the parallel connection, thereby charging the batteries 10A and 10B. On the other hand, when the potential difference between the voltage VA1 of the battery 10A and the voltage VB1 of the battery 10B is equal to or greater than the threshold value, the control unit 50 calculates the charging time based on the actual voltage increase amount and the potential difference per unit time of the battery 10B when the voltage VB1 of the battery 10B is smaller than the voltage VA1 of the battery 10A. For example, when the actual voltage increase per 1 second is 3V and the potential difference is 3V, the control unit 50 calculates the charging time to be 1 second. Then, the control unit 50 individually charges the battery 10B between time T4 and time T5 based on the calculated charging time. After charging the battery 10B, when the potential difference between the voltage VA1 of the battery 10A and the voltage VB2 of the battery 10B is smaller than the threshold value, the control unit 50 turns on the switch sw_ A, SW _b at time T6 to switch the connection of the batteries 10A and 10B to the parallel connection, and charges the batteries 10A and 10B. At this time, the charging current Ia flowing through each of the batteries 10A and 10B connected in parallel is about half of the maximum current Imax of the quick charger CG.

Next, an operation example of the power supply device 1 will be described with reference to a flowchart. Fig. 6 is a flowchart showing an example of the operation of the power supply device 1 according to the embodiment. When switching from the series connection to the parallel connection to charge, the control unit 50 first turns off the switch sw_ A, SW _ B, SW _c (step S1). Next, the control unit 50 detects the initial voltage of the battery 10A by the voltage detection unit 30A, and detects the initial voltage of the battery 10B by the voltage detection unit 30B (step S2). Next, the control unit 50 connects the battery 10A and the quick charger CG separately without connecting the battery 10B and the quick charger CG by turning on the switch sw_a (step S3). Then, the control unit 50 supplies the electric power of the constant current from the quick charger CG to the battery 10A for a predetermined period of time, and detects the voltage VA of the battery 10A by the voltage detection unit 30A (step S4). Next, the control unit 50 connects the battery 10B and the quick charger CG separately from each other without connecting the battery 10A and the quick charger CG by turning on the switch sw_b (step S5). Then, the control unit 50 supplies the electric power of the constant current from the quick charger CG to the battery 10B for a predetermined period of time, and detects the voltage VB of the battery 10B by the voltage detection unit 30B (step S6).

The control unit 50 determines whether or not the potential difference between the voltage VA of the battery 10A and the voltage VB of the battery 10B is smaller than a threshold value (step S7). When the potential difference between the voltage VA of the battery 10A and the voltage VB of the battery 10B is smaller than the threshold value (yes in step S7), the control unit 50 turns on the switch sw_ A, SW _b to switch the connection of the batteries 10A and 10B to the parallel connection, and charges the batteries 10A and 10B (step S8). When the remaining capacity of each battery 10A, 10B reaches 100% and the parallel charging is completed, the control unit 50 turns off the switch sw_ A, SW _b and the parallel charging is completed (step S9).

In step S7, when the potential difference between the voltage VA of the battery 10A and the voltage VB of the battery 10B is equal to or greater than the threshold value (step S7; no), the control unit 50 calculates the charging time of the battery 10A when the voltage VA of the battery 10A is smaller than the voltage VB of the battery 10B (step S10; yes) (step S11). The control unit 50 calculates the charging time based on, for example, the actual voltage increase per unit time of the battery 10A and the potential difference. Then, the control unit 50 connects the battery 10A and the quick charger CG separately by turning on the switch sw_a during the calculated charging time, and supplies the battery 10A with electric power of a constant current from the quick charger CG for a predetermined period of time to charge the battery 10A (step S12). Next, the control unit 50 detects the voltage VA of the battery 10A by the voltage detection unit 30A (step S13), returns to step S7 described above, and determines whether or not the potential difference between the voltage VA of the battery 10A after charging and the voltage VB of the battery 10B is smaller than the threshold value.

In step S10 described above, when the voltage VB of the battery 10B is smaller than the voltage VA of the battery 10A (step S10; no), the control unit 50 calculates the charging time of the battery 10B (step S14). The control unit 50 calculates the charging time based on, for example, the actual voltage increase per unit time and the potential difference of the battery 10B. Then, the control unit 50 connects the battery 10B and the quick charger CG separately by turning on the switch sw_b during the calculated charging time, and supplies the battery 10B with electric power of a constant current from the quick charger CG for a predetermined period of time to charge the battery 10B (step S15). Next, the control unit 50 detects the voltage VB of the battery 10B by the voltage detection unit 30B (step S16), returns to step S7 described above, and determines whether or not the potential difference between the voltage VA of the battery 10A and the voltage VB of the battery 10B after charging is smaller than the threshold value.

As described above, the power supply device 1 according to the embodiment includes: a chargeable and dischargeable battery 10A and a battery 10B; a voltage detection unit 30A that detects the voltage VA of the battery 10A; a voltage detection unit 30B that detects the voltage VB of the battery 10B; a switching unit 40 that switches the connection of the battery 10A and the battery 10B to a series connection or a parallel connection; and a control unit 50 for controlling the switching unit 40. When the connection of the battery 10A and the battery 10B is switched from the series connection to the parallel connection and the battery 10A and the battery 10B are charged by the external charger CG, the control unit 50 switches the connection of the battery 10A and the battery 10B to the parallel connection to charge the battery 10A and the battery 10B without switching the connection of the battery 10A and the battery 10B to the parallel connection and without charging the larger voltage but separately charging the smaller voltage when the potential difference is smaller than the threshold value when the potential difference is equal to or greater than the predetermined threshold value.

According to this configuration, when the charging voltage of the electric power supplied from the quick charger CG is a relatively high voltage (for example, about 1000V), the power supply device 1 can switch the connection of the batteries 10A and 10B to the series connection to charge the batteries 10A and 10B in series. On the other hand, when the charging voltage of the electric power supplied from the quick charger CG is relatively low (for example, about 500V), the control unit 50 can switch the connection of the batteries 10A and 10B to the parallel connection to charge the batteries 10A and 10B in parallel. That is, the power supply device 1 can correspond to the quick chargers CG of respective specifications in which charging voltages are different. At this time, since the power supply device 1 equalizes the voltages of the batteries 10A and 10B by charging and connects the batteries 10A and 10B in parallel, it is possible to prevent an excessive rush current from flowing between the batteries 10A and 10B due to a potential difference. As a result, the power supply device 1 can appropriately charge the respective batteries 10A and 10B that can be switched between the series connection and the parallel connection. Since the power supply device 1 charges the smaller voltage alone in the voltage equalization process, the voltage equalization process can be performed without wasting energy, compared with the conventional control of discharging the battery and equalizing the voltage. Since the power supply device 1 does not perform adjustment by discharge during the voltage equalization process, an increase in the charging time can be suppressed. The power supply device 1 can reduce the number of components such as a discharge resistor and a switch required for equalizing the voltage by discharging the battery as in the prior art, and can suppress an increase in the number of components.

In the power supply device 1 described above, the control unit 50 controls the switching unit 40 to connect the external charger CG to the battery 10A, and supplies the constant-current power from the external charger CG to the battery 10A for a predetermined period of time, and controls the switching unit 40 to connect the external charger CG to the battery 10B, and supplies the constant-current power from the external charger CG to the battery 10B for a predetermined period of time. The voltage detection unit 30A detects the voltage VA of the battery 10A when the battery 10A is supplied with electric power of a constant current from the external charger CG. The voltage detection unit 30B supplies the voltage VB of the battery 10B when the battery 10B is supplied with electric power of a constant current from the external charger CG. The control unit 50 calculates the actual voltage increase per unit time of the battery 10A for a predetermined period of time based on the voltage VA of the battery 10A detected by the voltage detection unit 30A. The control unit 50 calculates the actual voltage increase per unit time of the battery 10B for a predetermined period of time based on the voltage VB of the battery 10B detected by the voltage detection unit 30B. When the potential difference between the batteries 10A and 10B is equal to or greater than the threshold value, the control unit 50 calculates the charging time based on the actual voltage increase amount and the potential difference per unit time of the battery 10A when the voltage VA of the battery 10A is smaller than the voltage VB of the battery 10B, and charges the battery 10A based on the calculated charging time. On the other hand, when the voltage VB of the battery 10B is smaller than the voltage VA of the battery 10A, the control unit 50 calculates a charging time based on the actual voltage increase amount and the potential difference of the battery 10B per unit time, and charges the battery 10B based on the calculated charging time. According to this configuration, the power supply device 1 can perform the voltage equalization process while charging at the maximum current Imax of the external charger CG, and thus can suppress an increase in the charging time. Since the power supply device 1 charges the batteries 10A and 10B based on the calculated charging time, an increase in the number of times of charging the battery having a smaller voltage alone can be suppressed as compared with the case of charging based on the preset charging time. As a result, the power supply device 1 can appropriately charge the respective batteries 10A and 10B that can be switched between the series connection and the parallel connection.

Modification example

Next, a modification of the embodiment will be described. In the modification, the same reference numerals are given to the same components as those of the embodiment, and detailed description thereof is omitted. Fig. 7 is a block diagram showing a configuration example of a power supply device 1A according to a modification of the embodiment. The power supply device 1A according to the modification differs from the power supply device 1 according to the embodiment in that the voltages VA and VB of the batteries 10A and 10B are detected by a common voltage detection unit 30C.

The power supply device 1A includes a battery cell 10, a current detection unit 20, a voltage detection unit 30C, a switching unit 40, a control unit 50, a charging relay RY1, and a main relay RY2.

The charging relay RY1 is provided in the fast charging path, and is turned on based on the switching signal output from the control unit 50, so that the current of the electric power supplied from the fast charger CG to the batteries 10A and 10B is energized, and is turned off based on the switching signal output from the control unit 50, so that the current of the electric power supplied from the fast charger CG to the batteries 10A and 10B is cut off.

The main relay RY2 is provided in a path for supplying electric power to the inverter IV, and is turned on based on a switching signal outputted from the control unit 50, so that the current of electric power supplied from each of the batteries 10A and 10B to the inverter IV is energized, and is turned off based on a switching signal outputted from the control unit 50, so that the current of electric power supplied from each of the batteries 10A and 10B to the inverter IV is turned off.

One end of the voltage detection unit 30C is connected between the positive-side charging relay RY1 and the connection point P2, and the other end is connected between the negative-side charging relay RY1 and the connection point P1. The voltage detection unit 30C detects the voltage VA of the battery 10A in a state where the switch sw_a is on and the switch sw_ B, SW _c, the charging relay RY1, and the main relay RY2 are off. The voltage detection unit 30C is connected to the control unit 50, and outputs the detected voltage VA of the battery 10A to the control unit 50. In addition, the voltage detection unit 30C detects the voltage VB of the battery 10B in a state where the switch sw_b is on and the switch sw_ A, SW _c, the charging relay RY1, and the main relay RY2 are off. The voltage detection unit 30C outputs the detected voltage VB of the battery 10B to the control unit 50.

As described above, the power supply device 1A according to the modification detects the voltages VA and VB of the respective batteries 10A and 10B by the common voltage detection unit 30C, and therefore, it is possible to prevent voltage errors from occurring due to the difference in the voltage detection units, and it is possible to suppress a decline in the accuracy of the voltage equalization process.

In the above description, the example in which the current detected by the current detecting unit 20 is input to the control unit 50 has been described, but the present invention is not limited to this, and for example, a current value during rapid charging may be input from the rapid charger CG through communication.

The control unit 50 has been described as an example in which the voltages VA and VB detected by the voltage detection units 30A and 30B are input, but the present invention is not limited thereto, and may be applied to a case where the voltages of the batteries 10A and 10B can be obtained from a battery management system (BMS; battery Management System) and a battery voltage sensor (CVS; cell Voltage Sensor) provided in the batteries 10A and 10B, for example.

The power supply device 1 has been described as an example having 2 batteries 10A and 10B, but may have 3 or more batteries.

Claims

1. A power supply device, comprising:

a1 st cell and a 2 nd cell, the 1 st cell and the 2 nd cell being capable of charge and discharge;

a voltage detection unit that detects voltages of the 1 st cell and the 2 nd cell, respectively;

a switching unit that switches connection of the 1 st cell and the 2 nd cell to a series connection or a parallel connection; and

a control section that controls the switching section,

when the connection between the 1 st battery and the 2 nd battery is switched from the series connection to the parallel connection and the 1 st battery and the 2 nd battery are charged by an external charger, if a potential difference between the voltage of the 1 st battery detected by the voltage detection unit and the voltage of the 2 nd battery detected by the voltage detection unit is equal to or greater than a predetermined threshold value, the control unit does not switch the connection between the 1 st battery and the 2 nd battery to the parallel connection so as not to charge the 1 st battery and the 2 nd battery to the larger voltage and to charge the 1 st battery and the 2 nd battery to the smaller voltage alone, and if the potential difference is smaller than the threshold value, the control unit switches the connection between the 1 st battery and the 2 nd battery to the parallel connection and charges the 1 st battery and the 2 nd battery,

the control section controls the switching section and connects the external charger with the 1 st battery and supplies electric power of a constant current from the external charger to the 1 st battery for a certain period of time, and controls the switching section and connects the external charger with the 2 nd battery and supplies electric power of a constant current from the external charger to the 2 nd battery for a certain period of time,

the voltage detection unit detects the voltage of the 1 st battery when the electric power of a constant current is supplied from the external charger to the 1 st battery, and detects the voltage of the 2 nd battery when the electric power of a constant current is supplied from the external charger to the 2 nd battery,

the control section calculates an actual voltage increase amount per unit time of the 1 st battery in the certain period based on the voltage of the 1 st battery detected by the voltage detection section, and calculates an actual voltage increase amount per unit time of the 2 nd battery in the certain period based on the voltage of the 2 nd battery detected by the voltage detection section,

when the potential difference is equal to or greater than the threshold value, when the voltage of the 1 st battery is smaller than the voltage of the 2 nd battery, a charging time is calculated based on the actual voltage increase per unit time of the 1 st battery and the potential difference, the 1 st battery is charged based on the calculated charging time, and when the voltage of the 2 nd battery is smaller than the voltage of the 1 st battery, a charging time is calculated based on the actual voltage increase per unit time of the 2 nd battery and the potential difference, and the 2 nd battery is charged based on the calculated charging time.